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Elite Veteran
Posts: 1102
 
Location: Hayward, Calif | Hey Guys, I was checking out my extra wheels and the backspace measurements. Didn't realize I had this many different wheels. I'm pretty sure I'm checking this the right way, if not someone say something. All of the wheels have a 4 1/2 on 5 center. The first 2 pics are a 15" wheel, 2nd 2 pics are a 14" wheel. The backspacing I'm getting on the 15" wheel is 3 3/4. I also have a pair of 15" wheels with 3 3/8 backspacing. I realize the larger the backspace measurement, the closer the tire will be to the spring. Near as I can tell this wheel has a 5 1/2" width, a bit hard to be accurate with the tire still on. The 14" wheels were on the 59 Dodge when I got it. I have 2 wheels with 3 1/8 spacing and 2 wheels with 3 1/4 spacing. This looks a bit odd. All appear to be 5" wheels. FSM shows 5" or 5 1/2" wheels, but doesn't show backspacing measurement. I saw a pic/diagram somewhere that showed how to take these measurements, but don't remember where I saw it. The wife wants chrome wire wheels on this car, so would be a good idea to know what I'm talking about before I spend $1000 on wheels. Any info would be appreciated. Jerry
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 wheels 001.jpg (130KB - 84 downloads)
wheels 002.jpg (116KB - 93 downloads)
wheels 003.jpg (123KB - 84 downloads)
wheels 004.jpg (103KB - 88 downloads)
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Expert
Posts: 3402
Location: Chestertown, NY ( near Lake George) | That is the correct way to measure back spacing. |
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Expert 5K+
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Location: WHEELING,WV.>>>HOME OF WWVA | almost but not quite 59 . the video is a little lengthy to get the correct way but its real simple when apply'd ------------------------------------------later
https://www.youtube.com/watch?v=n96lE8jdMlQ |
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Expert 5K+
Posts: 7418
Location: northern germany | 60 dart - 2015-01-21 8:28 PM
almost but not quite 59 . the video is a little lengthy to get the correct way but its real simple when apply'd ------------------------------------------later
https://www.youtube.com/watch?v=n96lE8jdMlQ
no, that is not correct. you do not measure the lip. 59 measured it correctly. iirc, from what i learned in school, to measure it 100% correct you even have to subtract the rim material thickness. some wheels have a taller lip some don't but the lip does not affect the location of the tire. at least thats how its measured this side of the pond.
Edited by 1960fury 2015-01-22 9:46 AM
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Expert 5K+
Posts: 8948
Location: WHEELING,WV.>>>HOME OF WWVA | so , i guess all the wheel builders are wrong , ok . i can live with that but i think you're thinking of offset not back spacing
which are two different measurements--------------------------------------------later
Edited by 60 dart 2015-01-22 12:19 AM
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Expert 5K+
Posts: 7418
Location: northern germany | could be but since tires are wider and larger than rims they mostly create the clearance issues and the wheel lip has nothing to do with tire location so its irrelevant. if you measure the backspacing on a steel rim that way and you order an aluminum rim using that measurement you could get clearance problems.
correct, i checked, over here when shopping for tires we don't even know the term "backspacing" so i thought offset is the same thing because its always used as factor on US wheels. why? i do not know since its actually not important, misleading and can lead to rubbing tires and altered suspension geometry.
Edited by 1960fury 2015-01-22 10:23 AM
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Expert 5K+
Posts: 8948
Location: WHEELING,WV.>>>HOME OF WWVA | ok , let me explain why back spacing is needed in my feeble way . take two wheels by the same manufacturer with the same offset . one wheel has a wider tire , it rubs . lets say the back spacing is 3 3/4" . now get
a new wheel with the same offset and use the same size tire that was rubbing but with the back spacing of 3 1/4" it doesn't rub . the offset didn't change but the back inner part of the wheel past the back spacing was reduced by 1/2 inch allowing the bigger tire to be used . hope i explained it the right way . -------------------------------------later
Edited by 60 dart 2015-01-22 6:15 PM
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Expert 5K+
Posts: 7418
Location: northern germany | 60 dart - 2015-01-22 6:09 PM
ok , let me explain why back spacing is needed in my feeble way . take two wheels by the same manufacturer with the same offset . one wheel has a wider tire , it rubs . lets say the back spacing is 3 3/4" . now get
a new wheel with the same offset and use the same size tire that was rubbing but with the back spacing of 3 1/4" it doesn't rub . the offset didn't change but the back inner part of the wheel past the back spacing was reduced by 1/2 inch allowing the bigger tire to be used . hope i explained it the right way . -------------------------------------later
see, thats the problem and why i thought the lip and rim material thickness is not measured. the way backspacing is measured is inaccurate since the lip/thickness, that has no affect on tire location at all, is included. hence the position of the tire is determined by offset, not backspacing. period.
so wheel width and offset is all you need to know. if you change to a wider rim simply do the math and you will know if you run into clearance issues or not. unless you have a situation where the rim edge creates clearance problems (unlikely) backspacing is not important as TRUE backspacing is determined by offset.
so shop wheels by offset and not backspacing, that changes with wheel design and rim material used (without altering the location of the tire).
Edited by 1960fury 2015-01-22 7:09 PM
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Expert 5K+
Posts: 8948
Location: WHEELING,WV.>>>HOME OF WWVA | the site below is from australia and answers the original question about half way down . if anyone needs more of how to measure back spacing i can put up 10 or 20 more
links to sites that state the same thing ----------------------------------------------later
http://www.wheelsrus.com.au/blog/tech/wheel-101-wheel-terminology-e...
from US MAGS , harrisburg , pa
http://www.cjponyparts.com/us-mags-standard-wheel-15x8-silver-with-...
http://www.cjponyparts.com/us-mags-standard-wheel-18inx9in-chrome-1...
Edited by 60 dart 2015-01-23 12:20 AM
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Elite Veteran
Posts: 1102
Location: Hayward, Calif | Way to go Chuck!! Right On! I talked to a tire shop and he also mentioned that positive and negative thing. Jerry |
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Expert 5K+
Posts: 7418
Location: northern germany | 60 dart - 2015-01-23 12:10 AM
the site below is from australia and answers the original question about half way down . if anyone needs more of how to measure back spacing i can put up 10 or 20 more
links to sites that state the same thing ----------------------------------------------later
who questioned that? have you actually READ my messages? i do not think so. AGAIN, AS STATED ABOVE, YES, BACKSPACING INCLUDES THE WHEEL LIP AND RIM MATERIAL GAUGE. THIS MAKES IT IRRELEVANT WHEN CHOOSING RIMS AND DETERMINING THE LOCATION OF THE TIRE.
EXAMPLE, IF YOU GRIND OF THE INNER LIP OF AN ALUMINUM WHEEL BACKSPACING CHANGES BUT NOT THE LOCATION OF THE TIRE. got it now?
so this measurement is MISLEADING, thats why i thought, since backspacing is always mentioned, backspacing is measured without the wheel lip as explained above. if you know offset you know actual TIRE backspacing/location of the tire in the wheel housing.
Edited by 1960fury 2015-01-23 10:23 AM
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Expert 5K+
Posts: 7418
Location: northern germany | 60 dart - 2015-01-22 6:09 PM
take two wheels by the same manufacturer with the same offset . one wheel has a wider tire , it rubs . lets say the back spacing is 3 3/4" . now get
a new wheel with the same offset and use the same size tire that was rubbing but with the back spacing of 3 1/4" it doesn't rub . the offset didn't change but the back inner part of the wheel past the back spacing was reduced by 1/2 inch allowing the bigger tire to be used . hope i explained it the right way . -------------------------------------later
unlikely. 1/2 inch less backspacing with SAME offset means that the rim width was reduced reduced by 1 inch. the location of the tire (centerline) in the wheel housing did not change.
Edited by 1960fury 2015-01-23 10:24 AM
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Expert 5K+
Posts: 8948
Location: WHEELING,WV.>>>HOME OF WWVA | you're looking for a pissing match and you aint gettin one . -----------------------------------------------later , much later i hope ! |
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Expert 5K+
Posts: 7418
Location: northern germany | pissing match about what? facts have been stated. thats all. |
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Wheels--backspacing
